The referenced literature and patent disclosures are directed to fluorescent lamp systems in which fluorescent lamps are operated at a frequency high with respect to power network frequency, for example in the 10-100 kHz range. Such a system, for example, may include a fluorescent lamp operating circuit adapted to be connected to a power line circuit, operating at power line voltage and frequency, typically 110 V, 60 Hz, or 220 V, 50 Hz. The lamp circuit defines a positive and negative input terminal, across which an input capacitor is connected. A push-pull transistor frequency generator provides high-frequency power to the lamp or a plurality of lamps. The frequency generator typically includes two alternately conducting transistors, connected to a common junction. A current transformer has first and second windings connected, respectively, to the bases of the respective transistors to provide, in combination with another winding, an oscillatory circuit. Each one of the fluorescent lamps has an associated series resonance circuit which includes a resonance inductance and a coupling capacitor as well as a resonance capacitor connected to the filaments of the lamps. The referenced earlier application Ser. No. 023,481, filed Mar. 9, 1987, Fahnrich et al, assigned to the assignee of the present application and the disclosure of which is hereby incorporated by reference, describes an arrangement to insure that the wave shape or network power connected to the lamp circuit is not distorted beyond tolerance limits. This arrangement includes two diodes which are serially connected in forward current passing direction, defining a diode junction therebetween. The serially connected diodes have one end terminal connected to a terminal of the input capacitor and another end terminal connected to the network side of one electrode of the lamp. A capacitor connects the diode junction to the common junction of the push-pull connected transistors. The circuit also utilizes a power line choke connected between the network power supply terminals and the lamp circuit input terminals.
The system works well; it is versatile and can be used with single fluorescent lamps or a plurality of fluorescent lamps located, for example, in a single fixture. The fluorescent lamps can be serially connected. In one arrangement, the first electrode of a first lamp is connected over the resonance inductance with the center tap between the two transistors, and the second electrode of the last lamp in the series is connected with either the positive or the negative terminal of the network rectifier. The referenced application Ser. No. 023,481, filed Mar. 9, 1987, describes such an arrangement in detail. This arrangement includes an iron core choke in the network power frequency portion of the circuit, in order to smooth out any remaining peaks due to capacitor charging, and which might be fed back into the network, in order to provide a circuit which will not distort the wave shape and to meet all standardization and power network requirement with respect to wave shape and feedback characteristics of connected appliances or units.
The iron core choke requires substantial space; its dimensions are substantially larger than all other components of the circuit which can be constructed in miniaturized form. The arrangement, thus, because of the presence of the iron core choke, cannot easily be fitted within, for example, the base of a fluorescent lamp; the choke would be external to the base so that the entire connection system to connect a lamp and the associated circuitry to a power terminal plug cannot be integrated in the base or within a base-socket combination of a fluorescent lamp.